Cervical cancer disproportionately affects minority, immigrant, and low income women. Human Papillomavirus (HPV) vaccines have the potential to substantially prevent high-risk HPV infections and future cases of cervical cancer. However, recent studies show that HPV vaccine uptake in high risk groups remains low. Even with available programs that provide the vaccine for free to low income populations, multiple barriers, such as lack of geographic/spatial accessibility to safety-net immunization clinics, may prevent disadvantaged girls from obtaining the HPV vaccine. Current disparities in cervical cancer will likely persist as a result of HPV vaccine under-utilization among low income, ethnic minority populations. This cross-sectional study will examine geographic/spatial access to care and neighborhood factors, in addition to individual level factors, that influence HPV vaccine initiation (receiving e 1 dose of the HPV vaccine) among low-income, minority girls in Los Angeles County (LAC). The study will build on primary data collected from mothers of HPV vaccine age-eligible girls who primarily reside in disadvantaged areas of LAC and routinely access the county safety-net system. This individual-level data will be linked at the census tract level to neighborhood socio-demographic data from the U.S. Census Bureau and neighborhood cervical cancer risk data from the LAC Sexually Transmitted Diseases Program. Geographic information systems mapping techniques will be employed to create geographic/spatial access measures (shortest travel distance to clinic, coverage of e 1 clinic within a 3-mile radius of household) using residential addresses of vaccine age-eligible girls and locations of safety-net immunization clinics. The study will evaluate whether spatial access to immunization clinics is associated with HPV vaccine initiation, as well as whether the relationship between spatial access and vaccine initiation is modified by individual race/ethnicity, while controlling for other individual level risk factors. Hierarchical logistical regression modeling will also be used to assess the impact of neighborhood factors (socio-demographic characteristics and cervical cancer risk), in addition to spatial access and individual level risk factors, on HPV vaccine initiation. The study is unique in that it moves beyond individual level predictors to assess geographic and neighborhood factors that impact HPV vaccine initiation in an underserved, urban population. Study results will inform local county health officials about factors that contribute to low HPV vaccine utilization and provide information relevant to resource allocation decisions for cancer prevention and control programs in LAC. Results will also inform health policymakers and researchers on geographically based interventions that could improve HPV vaccine uptake. PUBLIC HEALTH RELEVANCE: This study will examine the impact of geographic/spatial access to safety-net immunization clinics and other neighborhood socio-demographic and cervical cancer risk factors on HPV vaccine initiation among low- income, ethnic minority girls in Los Angeles County. Individual survey data, collected from mothers of HPV vaccine age-eligible girls, will be combined with data from the Los Angeles County Department of Public Health STD Program and the U.S. Census Bureau to conduct geographic information systems (GIS) mapping and multi-level analysis. Findings will provide an understanding of how spatial and neighborhood factors influence HPV vaccine uptake in a large urban setting and inform cervical cancer control programs and policies.